It is now recognized that the physical chemical structure of whole human blood has been successfully duplicated in a composition of matter known as Synthetic Whole Blood, as disclosed in Applicants' U.S. Pat. No. 4,343,797. It is now also recognized that Synthetic Whole Blood is a distinct entity, fundamentally different from the preparations referred to in the scientific literature as "blood substitutes".
An appropriate two-phase aqueous liquid system (i.e. coacervate system) is fundamental to preparation of synthetic whole blood and its companion product, synthetic hematocrit. U.S. Pat. No. 4,343,797 contains the comment, "In the practice of this invention the underlying principle is that any molecule or combination of molecules capable of forming a non-toxic, two-phase, aqueous liquid system can be . . . used to prepare the requisite coacervate system." Further study of the discovery of this principle by the inventors makes it possible to specify this principle in greater detail. The present disclosure further exemplifies this principle.
One category of coacervate systems useful to prepare synthetic whole blood contains among its principal components, (1) a suitable protein, i.e. albumin, gelatin, modified fluid gelatin, etc.; (2) a coacervating surface active molecule such as lecithin; each of these components possessing opposing surface charges; and (3) hemoglobin in the form of synthetic liposomes containing stroma free hemoglobin or stroma free hemoglobin per se, or microencapsulated hemoglobin.
The fundamental components of another category of coacervate systems useful to prepare synthetic whole blood contains (1) two similar or two different protein molecules, i.e. gelatin, modified fluid gelatin, etc., each with a surface charge that opposes the surface charge of the other; and (2) stroma free hemoglobin, microencapsulated hemoglobin or synthetic liposomes containing stroma free hemoglobin.
Appropriate physiologically useful additives can be readily introduced into the compositions derived from either class of the coacervate systems described above.
A number of considerations warrant the development of an alternative version of the Synthetic Whole Blood preparation, as disclosed in U.S. Pat. No. 4,343,797. Principal among these is the probability that a small but medically significant number of persons may be sensitive to one or more of the ingredients of the composition referred to above.